Vacuum cleaners are commonly used household appliances for removing dust and debris from various surfaces.
Generally, a vacuum cleaner has a filter for removing dust from dust laden air flowing through the vacuum cleaner. After some time of usage dust adheres to the filter surface which leads to a pressure drop and reduced vacuum cleaning efficiency. Thus, cleaning of the filter is necessary to remove the particulate matter, such as dust, hair and fibers, from the filter. Drawbacks of prior art filters are that they are often not easy to clean. Further, prior art filters require sometimes water to be cleaned, thereby rendering the filter unusable for vacuum cleaning during the time needed for drying off. Further, in case of a clogged filter, it is also common to replace the filter with a new one for regaining vacuum cleaning efficiency, which costs extra.
WO2007/117196 discloses a hand held vacuum cleaner comprising a housing with a dust container having an inlet for dust laden air, a filter unit with a filter body and a motor fan unit for generating a flow of air through the inlet and through the filter unit. The filter body is flexible and the vacuum cleaner further comprises dust removing means configured to collapse and expand the flexible filter body in response to a force applied to the dust removing means. Although such a solution provides a vacuum cleaner that is relatively easy to use with a filter that is dry, the efficiency of the vacuum cleaner is still limited.
Thus, there is a need for providing new filters (or filter units) that would address at least some of the above mentioned issues.